Category | 2018 | 2015 | 2013 | 2010 | 2007 | |
---|---|---|---|---|---|---|
Don't know | 0 | 1 | 0 | 1 | 1 | |
I have never heard of it (%) | 29 | 38 | 26 | 33 | 35 | |
I've heard of it but I do not know what it is (%) | 30 | 30 | 30 | 28 | 30 | |
I've heard of it and I know what it is (%) | 41 | 31 | 44 | 38 | 35 |